Do not know front spring rate, sorry. As a way of comparison. the 75Nm and 85Nm spring rates convert to 7.65 and 8.67 kilograms of force. You'll find the rates at Race Tech in Kg/mm I think.
If anybody remembers back to my front fork thread, Race Tech was not able to supply most of the correct bushings and seals for the front forks. They are Marzocchi Magnum 45mm forks. Turns out same as on like 98-99 KTM 200 according to one kid I talked too, as well as some Husky's and others. I turned to SF Moto for the fork internals and they were same price if not cheaper than Race Tech's, plus they shipped quicker.
Compared to other large singles the Baghiras are much better sprung for normal weight Brits/Germans/Aussies/Americans..
Stock KLR rear spring is like 5.1 kg/mm and stock DR650 is about 6.5 kg/mm. So I figured front must be too.
I too considered stiffening front (almost 100 kg rider) but since the bike is well balanced and I decided I'd like to keep most of the 11 inches of suspension travel I decided against stiffening it up to be like a sport bike.